My intention in seeking the Physician Scientist Award is to prepare myself for a career as an independent investigator in Neuroendocrinology. As outlined in the Research Plan and in the statements which follow it, my development would occur in two phases. In Phase I, I will undertake a formalized plan of study encompassing course work offered through the Department of Pharmacological and Physiological Sciences and the Committee on Neurobiology, and laboratory research under the guidance of the primary sponsor, Dr. Richard Miller. The basic Research Plan involves a detailed investigation of the properties of voltage-sensitive calcium channels in rat pituitary cells, and of their participation in the mechanisms of pituitary hormone secretion, using normal rat pituitary cell cultures. In conjunction with this, I will examine the role of endogenous opioid peptides in the regulation of pituitary function and the cellular mechanisms involved therein, using the same models, and assessing the involvement of calcium as a second messenger for opioid actions. In Phase II of the Award, I will investigate the role of opioid peptides in the menstrual-cycle dependent changes in the osmoregulation of vasopressin, and subsequently will examine the participation of vasopressin in the etiology of water-retentive symptoms of the Premenstrual Syndrome.